下扬子西部地区中二叠统孤峰组气源岩发育特征及控制因素

Characteristics and controlling factors of natural gas source rocks of Middle Permian Gufeng Formation in western part of Lower Yangtze Platform, China

白帆

BAI Fan

中国石化 石油物探技术研究院, 南京 211103

SINOPEC Geophysical Research Institute, Nanjing, Jiangsu 211103, China

近年来下扬子区的非常规天然气资源越来越得到重视。通过对下扬子西部地区中二叠统孤峰组主要野外剖面和钻孔样品的分析，研究了该区孤峰组气源岩发育特征及控制因素。该区孤峰组页岩厚度中心在芜湖一带，最大厚度大于150 m，页岩总有机碳（TOC）含量较高，主要介于1.0%~4.0%，平均约为3.41%，且不同体系域中的TOC含量存在明显差异；干酪根类型主要为Ⅱ2型和Ⅲ型；孤峰组页岩整体处于热成熟晚期，位于生烃干气窗范围内。孤峰组富有机质层段的形成与火山作用及其与之紧密伴生的热水流体活动相关。火山作用及热水流体活动将地球深部物质带到表层，使得水体富营养元素，引起生物勃发，形成高生产力，进而为好烃源岩的形成提供良好的物质基础。

Unconventional natural gas resources in the Lower Yangtze region have caused plenty of interests of the Chinese energy companies in recent years. The developing characteristics and controlling factors of natural gas source rocks in the Middle Permian Gufeng Formation were studied by analyzing the typical field profiles and boreholes. The thickness center of Gufeng Formation shale locates in the Wuhu area, and the maximum of thickness is greater than 150 m. The total organic carbon (TOC) content of shale is relatively high, mainly ranging from 1.0% to 4.0%, with an average value of about 3.4%, and there are significant differences for the TOC content of different systematic tracts. Kerogens are mainly of types Ⅱ2 and Ⅲ. The Gufeng Formation shale is in the late stage of thermal maturity, and within the range of the dry gas window. The development of organic-rich beds in the Gufeng Formation was related to volcanism and its closely associated hydrothermal fluid activities. Volcanism and hydrothermal fluid activities brought materials from deep earth to surface, which enriched water body with nutrient-rich elements, caused biological bloom and formed high productivity, thus provided a good material for good source rocks.

国家科技重大专项“大型油气田及煤层气开发——重点探区页岩气资源评价” 2017ZX05036-001

https://doi.org/10.11781/sysydz202103468